<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>2.33</title>
</head>

<body>
    <script>
        function calculate(method, ...nums) {
            let result;
            if (!method || nums.length == 0) {
                alert('请传入参数！');
                return;
            }
            if (method == '*') {
                result = 1;
                for (let i = 0; i < nums.length; i++) {
                    result *= nums[i];
                }
            } else if (method == '+') {
                result = 0;
                for (let i = 0; i < nums.length; i++) {
                    result += nums[i];
                }
            }
            alert(result);
        }
        calculate("+", 1, 2); //3
        calculate("+", 1, 2, 3, 4, 5);   //15
        calculate("*", 1, 2, 3);   //6
        calculate("*", 1, 2, 3, 4, 5);   //120
    </script>
</body>

</html>